Find the Best Solar Panels for Your Home in 2018

An In-depth Guide

The price of solar panels has decreased dramatically over the last decade, making solar a great investment for homeowners looking to saving money and reduce their carbon footprint. But how do they work? How many do you need? And what are the best options based on your home and budget? Deciding which panels are best for you requires carefully evaluating a number of factors, including panel efficiency, your home energy needs, and your rooftop aesthetic tastes.

What Are the Best Solar Panels for You?

Step 1: Understanding How To Evaluate Solar Panels Specifications

You should learn a bit about what qualities and traits to look for in high quality solar panels.

Step 2: Identifying Your Home’s Needs

Read up on which panels will help cover your electric bill with free energy and which will also go best on your roof’s unique color and shape.

Step 3: Considering Your Budget, Electric Billim And Costs

Prices matter when trying to make solar work for your home. This section will focus on costs and ROI.

Step 1: Understanding How To Evaluate Solar Panels Specifications

How do solar panels work?

Let’s start with the basics: Solar panels create electricity by using the energy in sunlight to excite electrons and cause them to move in an electric current. Usually when sunlight hits an object, the energy in the sunlight is converted to heat. However, some materials can capture and transmit that energy in the form of an electric current.

What do panel energy ratings mean?

Each solar panel (or “module”) is made up of a collection of solar cells. Solar panels are classified by their maximum power output, measured in watts. The higher the wattage, the more power a panel will be able to produce. Using panels of higher wattage could enable you to invest in a system that requires fewer panels. For instance, a system of 10 panels rated at 200 watts will produce the same amount of energy (2,000 watts) as a system composed of 20 panels rated at 100 watts each. Using fewer panels could be an important consideration if you’re working with limited land or roof space.

What kinds of panels are there?

Most PV panels today can be classified as monocrystalline (“mono”) or polycrystalline (“poly”). The solar cells within polycrystalline panels have a lower silicon purity, making them less efficient and long-lived than mono panels. However, since it is expensive to purify silicon, monocrystalline panels are more expensive. Most PowerScout partners use monocrystalline panels because despite costing more, they are also more efficient and durable.

A third alternative, thin-film PV technology, has also taken off in recent years. However, despite being relatively inexpensive, thin-film PV panels require significantly more space and typically don’t last nearly as long as either mono or poly panels. Thin film technology is rarely used for residential purposes.

Which panels are the most efficient?

Apart from cost and aesthetics, the most important consideration when choosing a solar panel is its efficiency. Efficiency refers to the ability of a solar panel to convert sunlight into electricity. The higher the efficiency, the more sunlight your panel will be able to use.

Most solar panels have efficiency rates of around 15 percent. Low-efficiency panels might have efficiency rates of about 10 percent. But high-efficiency panels have rates approaching 20 percent or more. Here’s an interesting video that explores the high-efficiency SunPower panels:

Every year seems to bring more efficient solar panels. In 2015, SolarCity achieved a record efficiency of 22 percent. Just one week later, Panasonic broke that record with slightly more efficient panels. Last year, SunPower’s rooftop solar modules broke the 24 percent efficiency barrier. And earlier this year, Japanese solar company Kaneko set another new record with its 26.6-percent-efficient panels.

Kaneko’s high-efficiency panels are premised on a manufacturing technique that allows them to minimize band gaps – spaces where electrons cannot exist and sunlight is, therefore, wasted. The Kaneko engineers didn’t invent the technique, known as thin-film heterojunction optimization, but they improved upon it in order to attain their record-breaking efficiency.

In research settings, solar panel efficiencies have reached even higher. In 2014, researchers from University of New South Wales (UNSW) in Australia developed a panel with an efficiency rating of over 40 percent.

That same year, the Fraunhofer Institute for Solar Energy Systems (FISES), semiconductor and microelectronics manufacturer Soitec, and nanotechnology firm CEA-Leti collaborated to develop solar cells (but not solar panels) that were even more efficient. The French and German research team created cells that were 46 percent efficient.

The researchers from UNSW and from FISES both achieved their high efficiency rates by “splitting” the sunlight with a multijunction solar cell. In multijunction solar cells, four traditional (single-junction) cells are stacked on top of one another. Each single-junction cell captures light of a different bandwidth, enabling the cell to utilize more of the sun’s energy. Traditional single-junction solar cells have theoretical upper efficiency limits of about 36 to 44 percent. Multijunction cells, on the other hand, have theoretical efficiency limits of over 86 percent. Current efficiency rates could be improved even further if the light passed through five single-junction cells rather than just four.Another cell type that can yield high efficiency is the passivated emitter and rear cell (PERC). PERCs are different from most other solar cells, which are known as aluminum back surface field (Al-BSF) cells. Unlike Al-BSF cells, PERCs are backed by an insulating layer that improves the reflectivity of the aluminum electrode. As a result, PERCs receive more light than Al-BSF cells under identical conditions. Today, Al-BSF cells account for about 80 percent of all solar cells on the market, but PERCs are becoming more common. Analysts expect that PERCs will be utilized in 60 percent of all solar panels by 2027.

The way in which the electric current is transferred from the silicon wafer within the solar cells also affects efficiency. The surface of the solar cell is lined with busbars (thick strips of metal) and fingers (thinner strips of metal) that link cells within a panel and transmit it into your home. But sunlight cannot reach the areas covered by the fingers and busbars. To increase panel efficiency, a growing number of manufacturers are finding ways to produce solar panels without busbars.

At the same time, another contingent of manufacturers is increasing the number of busbars to five, up from the standard three or four. By increasing the number of busbars, the cell receives less sunlight, but it also enjoys improved electrical transmission and, therefore, a higher efficiency rate.

Another high-efficiency design choice is increasing the amount of light that is reflected and trapped within the module. In addition to the PERCs revolution now underway, solar panel manufacturers are finding new ways to capture the reflections that occur inside the panels. For instance, many manufacturers are utilizing better antireflective coating on the panels’ faces, thereby allowing more light to pass into the solar cell.

The materials that are used to create a solar panel also affect efficiency rates. Monocrystalline panels tend to have lower rates of impurities and, therefore, higher efficiencies than polycrystalline solar panels.

Analysts predict that at the current rate of technological development, high-efficiency solar panels in 2027 will be an average of 5 percentage points more efficient than today’s high-efficiency panels. It doesn’t sound like a big improvement, but considering most of today’s high-efficiency panels are only about 21 percent efficient, a jump to 26 percent efficiency represents a 23 percent improvement over today’s panels. Future improvements in efficiency (for both high-efficiency and standard-efficiency panels) are important for making clean solar energy more affordable, since the more efficient solar panels are, the fewer of them you’ll need to power your home.

For the average homeowner, high-efficiency panels are a good investment if you’re installing them in a limited space, since more efficient panels tend to be smaller compared to a lower-efficiency panel of equal wattage. For example, if one 250-watt panel has an efficiency of 20 percent and another 250-watt panel has an efficiency of 15 percent, both will provide 250 watts under ideal conditions, but the panel with the 20 percent efficiency will be smaller. To get the most out of a small area, high-efficiency panels are the way to go.

How long do solar panels last?

One of the biggest questions homeowners have about solar panels is how long they last. Generally, solar panels will last between 25 and 30 years, but a number of factors complicate that estimate. The materials used to produce a solar panel will affect its longevity, as will the panel’s design and the conditions under which the panel is used.

A 2012 study from the National Renewable Energy Laboratory found that solar panel output falls by an average of about 0.8 percent annually. This percentage is called the solar panel degradation rate, and it varies with different solar panels. High-end solar panels, for instance, boast a degradation rate of closer to 0.3 percent.

The degradation rate is primarily determined by the type of solar cell used in the panel’s production. The solar cell is the heart of the solar panel, and converts light energy into electricity using a complex chemical and physical process known as the photovoltaic effect.

There are two major types of commercial solar cells. Crystalline silicon cells are the most common type. In 2016, crystalline silicon cells accounted for over 90 percent of all solar energy production. The other type is the thin-film solar cell.

Crystalline silicon cells are composed of seven basic layers, starting with a transparent adhesive that holds a glass cover over an anti-reflective coating. Beneath these elements are several silicon crystal layers where the photovoltaic effect occurs. These components are all sandwiched between two electrical contacts (one positive and one negative).

In thin-film solar cells, a photovoltaic material (amorphous silicon, cadmium telluride, or a copper-based absorber, for instance) is applied to glass, plastic, metal, or another substrate. These cells are potentially cheaper (depending on the materials used), but they’re also slightly less efficient than crystalline cells. And, as their name suggests, thin-film cells are lighter and more flexible than their crystalline silicon counterparts. Under normal conditions, both types of solar cells are expected to have roughly equivalent lifetimes.

The design of your solar cell also makes a difference in how long it will last. There are two main cell designs. Conventional cells are made of thin solar wafers with metal strips that run along their surface. These strips, known as busbars, are used to connect solar cells to one another and create higher voltages. But as these cells heat up, the metal expands, and as the cell cools at night, the metal contracts.

In most solar panels, the busbars are contained in insulated coverings, which prevents them from expanding or contracting too much. However, even a limited amount of movement can weaken the cell and cause its longevity to decline. Additionally, soldering along the busbars can cause microcracks that threaten the longevity of the whole panel.Newer solar panels are often made without busbars. This makes them more flexible (even if they’re made of the rigid crystalline silicon) and prevents the problems associated with busbar expansion and cracking.

Another variable that affects the longevity of a solar panel is its efficiency rate. The efficiency rate refers to how much solar energy a particular solar panel captures for use. Different manufacturers produce solar panels with different efficiency rates. Most experts agree that when a solar panel’s energy production declines by about 20 percent, it is considered a failure and should be replaced. Using this guideline, a panel that degrades at 0.8 percent annually will qualify as a failure in 25 years (which is why most solar panel manufacturers only warranty their panels for 25 years). However, some high-efficiency panels might actually produce more power after even a 50 percent decline in energy production than a lower-efficiency panel would after a 20 percent decline in energy production.

While solar panels are typically designed without moving parts, they do require some maintenance. For instance, keeping your panels clear of snow, leaves, and other debris can increase their longevity and maximize their energy output. Beyond that, there’s little you can do to extend the life of your solar panels－which is why it’s important to buy your solar panels from a reputable dealer and do your homework before making an investment in solar energy.

Step 2: Identifying Your Home’s Needs

Which panels are the most aesthetically pleasing?

The appearance of rooftop solar panels has evolved with advances in technology. Modern solar panels have a sleek design intended to maximize curb appeal.

Solar panel design can vary based on the make and model. There are broadly two types of conventional solar panels: polycrystalline panels which have a blue-gray color, and black monocrystalline panels. In addition to the cell type of the panel, the backsheet, the frame and presence of busbars can affect the appearance of solar panels.

Today, all-black panels (black solar cells with black backsheets and black frames) are considered the most aesthetically pleasing, and they’re rapidly becoming the industry standard.

Another solar product that has enjoyed increased popularity and challenged the traditional appearance of solar panels is the solar shingle. Solar shingles look like any other roofing shingle, but contain embedded solar cells. This removes the necessity of installing large, heavy solar panels on the roof. Instead, solar shingles double as the roof and produce electricity in the same way solar panels do.

Where should my panels be installed?

Most homeowners install solar panels on their roof, though, ground mounts are an attractive option if solar doesn’t work for your roof and you have land available to install solar panels. Shading, roof orientation, and the amount of sunlight in your region determine the feasibility of solar for your home. An ideal roof has no shading from trees or other obstructions, faces south, and receives a lot of sunlight throughout the year.

But even if it’s possible to install panels on your roof, you might not want to. Installing panels on open land allows you to align them in a way that truly maximizes their energy production. Rooftop panels, by contrast, often need to be oriented in close alignment with the roof.

Step 3: Considering Your Budget And Costs

Once you know the size of the system that you need, the next step to figuring out what solar will cost per watt in your state. It’s important to always get solar prices in per watt so that you can compare across different system sizes. There is some variability in price per watt across different states. In 2017, the average cost per watt across most states is roughly $3.00-$3.70.

Are some panels more affordable than others?

When it comes to solar panels, low cost doesn’t necessarily mean low quality. Solar panels are available at a wide variety of price points. When you’re investing in a solar energy system, it’s important to onlypay for what you need and not to overpay for hype. The best solar panels for your home and budget might not have the highest efficiency, the highest rating, or the highest price, but they’ll still get the job done.

Bloomberg New Energy Finance, a renewable energy research organization, classifies solar panels into three tiers based on whether the manufacturer provided panels for at least five large-scale projects that were financed by five different banks over the past two years. Lending institutions tend to have greater confidence in projects that utilize panels produced by firms that have been in the business for more than five years, invest heavily in research and development, and have vertically integrated manufacturing processes.

As a result, most majorutility-scale solar projects utilize these so-called “tier-one” panels rather than panels produced by firms that have not been in the business as long or that don’t invest much in research and development.

But you could save money by opting for tier-two or tier-three panels. A tier-two panel is produced by a small or medium-sized company that doesn’t invest much in research and development and has been in business for two to five years. A tier-three panel is produced by a firm that has been in business for less than two years and assembles solar panels but doesn’t produce its own solar cells.

Whatever you choose to buy, remember that solar panels are a long-term investment, and saving on up-front costs could mean paying more later if your panels end up performing below expectations. It’s important to not only think about the quality of the panels but also about the warranties and service agreements that come with them. Will the panel manufacturer service your system if there areissues or defects? What sort of service network do they provide? How long is the warranty? Tier-two and tier-three producers will probably not be able to match a tier-one producer in these regards, even if their panels are of comparable quality.

Chinese panels are also cheaper than those produced by American companies like SunPower, Mission Solar, and so on. The affordable prices offered by JA Solar, Jinko Solar, and other Chinese manufacturers has made them the panel of choice for many homeowners and commercial projects across India, Europe, the U.S., and South Africa.

Several Chinese manufacturers have even produced tier-one panels, including the aforementioned Jinko Solar, Trina, and JA Solar. Tier-one panels from lesser-known Chinese companies likeSuntech orChina Sunenergy could be even cheaper than those made by their more famous Chinese competitors.

Finally, you could purchase polycrystalline panels to keep your costs low. If you have enough space on your roof to add somewhat larger panels that cost less, there’s no reason to pay more for the higher efficiency offered by monocrystalline panels.

Pricing and Costs

Solar panel prices span a wide range based on their quality, brand, and energy production capacity. Figuring out which are right for your home can be tricky. Before investing in a solar energy system, it’s important to shop around and obtain quotes from a variety of panel installers and distributors. This will help you get a better sense of how much you should pay for your solar panels and protect you from paying too much. Since the actual installation costs can vary based on the conditions and location of your home, solar installers are often reluctant to post their panel prices online. But some solar distributors like Wholesale Solar and Go Green Solar regularly post current panel prices. The websites of some big box stores like Home Depot and Wal-Mart are also useful for browsing solar panels and comparing prices from various manufacturers.

We have a very long guide on solar panel costs that explores all the costs and pricing in more depth.

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Estimated savings are based on a projected annual utility rate increase of 3.5% over the life of the
system. Actual pricing and savings will vary and is not guaranteed. Savings depends on several
factors, including product type, system production, system size, geography, weather, shade,
electricity usage, full utilization of all available tax credits and rebates by the system owner,
and utility rate structures and rate increases.